The present invention is directed towards a new reagent system for determining the hemoglobin content of whole blood. The quantitative determination of hemoglobin in whole blood is one of the most frequently performed analyses in clinical chemistry. It is, therefore, desirable to develop new, safe and reliable methods for performing this analysis.
The most frequently performed spectrophotometric analysis uses a method known as the cyanomethemoglobin method which has been universally accepted and is now used worldwide. A serious drawback to the cyanomethemoglobin method is that the reagent is a highly toxic chemical and, therefore, extreme care must be used when handling this reagent.
An alternative method to the cyanomethemoglobin method is disclosed in U.S. Pat. No. 4,341,527. The patent discloses a water-soluble liquid nitrogen-free non-ionic detergent such as polyethyleneglycol p-alkylphenyl ether and various derivatives thereof. This approach uses a non toxic surfactant to stabilize the heme and hemoglobin derivatives of the denatured blood such that a photometric determination of the hemoglobin content of the blood sample can be performed. An unfortunate drawback to this method, however, is that because a surfactant is employed, the surface tension of the aqueous reagent solution is reduced, which presents problems in handling the reagent. In particular, the lower surface tension of the reagent presents problems in transferring the reagent by pipette. The low surface tension also presents problems in packaging the reagent because of the tendency to adhere to packaging surfaces. It is, therefore, desirable to develop a new reagent system for the determination of the hemoglobin content of whole blood which has the advantage of being non-toxic without reducing the surface tension which presents problems in processing and handling of the reagent.